我在用Debian 破坏者、10.7，我对 udev/udisks2/systemd 比较陌生，一直在努力去了解它们，也学到了很多东西，不过我似乎无法弄清楚如何既能防止 udisks2 自动将特定卷（SD 卡）安装为/media/$USER/foo，又能将其安装为/data。
以下是我迄今为止尝试过的：
$ grep /data /etc/fstab
UUID="3537-3761" /data exfat-fuse defaults,nofail,x-systemd.device-timeout=2ms 0 0
$ cat /etc/systemd/system/data-sdcard-mount.service
[Unit]
Description=Mount Data SD Card on /data
[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/mount /data
ExecStop=/bin/umount /data
$ cat /etc/udev/rules.d/99-data-sdcard.rules
ACTION=="add", \
SUBSYSTEM=="block", \
ENV{DEVTYPE}=="partition", \
ENV{ID_DRIVE_MEDIA_FLASH_SD}=="1", \
ENV{ID_NAME}=="SF256", \
ENV{ID_SERIAL}=="0x3db0a775", \
RUN+="/bin/systemctl start data-sdcard-mount", \
ENV{UDISKS_IGNORE}="1", \
OPTIONS="last_rule"
ACTION=="remove", \
SUBSYSTEM=="block", \
ENV{DEVTYPE}=="partition", \
ENV{ID_DRIVE_MEDIA_FLASH_SD}=="1", \
ENV{ID_NAME}=="SF256", \
ENV{ID_SERIAL}=="0x3db0a775", \
RUN+="/bin/systemctl stop data-sdcard-mount", \
OPTIONS="last_rule"
这是我在插入卡后（尽管登录到 MATE 后）在另一个终端窗口中看到的系统日志：
Feb 4 13:25:51 localhost kernel: [508706.027711] mmc3: new high speed SDXC card at address aaaa
Feb 4 13:25:51 localhost kernel: [508706.044472] mmcblk3: mmc3:aaaa SF256 238 GiB
Feb 4 13:25:51 localhost kernel: [508706.058372] mmcblk3: p1
Feb 4 13:25:51 localhost systemd[1]: Starting Mount Data SD Card on /data...
Feb 4 13:25:51 localhost mount[1734]: FUSE exfat 1.3.0
Feb 4 13:25:51 localhost mount[1734]: WARN: volume was not unmounted cleanly.
Feb 4 13:25:51 localhost mount.exfat-fuse: volume was not unmounted cleanly
Feb 4 13:25:51 localhost systemd[1]: data.mount: Unit is bound to inactive unit dev-disk-by\x2duuid-3537\x2d3761.device. Stopping, too.
Feb 4 13:25:51 localhost systemd[1]: Started Mount Data SD Card on /data.
Feb 4 13:25:51 localhost systemd[1]: Unmounting /data...
Feb 4 13:25:51 localhost systemd[14720]: data.mount: Succeeded.
Feb 4 13:25:51 localhost systemd[2920]: data.mount: Succeeded.
Feb 4 13:25:51 localhost systemd[1]: data.mount: Succeeded.
Feb 4 13:25:51 localhost systemd[1]: Unmounted /data.
Feb 4 13:25:52 localhost systemd[1]: Started Clean the /media/vanfan/Data mount point.
Feb 4 13:25:52 localhost udisksd[2010]: Mounted /dev/mmcblk3p1 at /media/vanfan/Data on behalf of uid 1000
它看起来像是安装到/data 但由于某种原因而被卸载。
以下是udisksctl info -b /dev/mmcblk3p1：
$ udisksctl info -b /dev/mmcblk3p1
/org/freedesktop/UDisks2/block_devices/mmcblk3p1:
org.freedesktop.UDisks2.Block:
Configuration: []
CryptoBackingDevice: '/'
Device: /dev/mmcblk3p1
DeviceNumber: 45825
Drive: '/org/freedesktop/UDisks2/drives/SF256_0x3db0a775'
HintAuto: true
HintIconName:
HintIgnore: false
HintName:
HintPartitionable: true
HintSymbolicIconName:
HintSystem: false
Id: by-uuid-3537-3761
IdLabel: Data
IdType: exfat
IdUUID: 3537-3761
IdUsage: filesystem
IdVersion: 1.0
MDRaid: '/'
MDRaidMember: '/'
PreferredDevice: /dev/mmcblk3p1
ReadOnly: false
Size: 255835766784
Symlinks: /dev/disk/by-id/mmc-SF256_0x3db0a775-part1
/dev/disk/by-label/Data
/dev/disk/by-path/platform-4809c000.mmc-part1
/dev/disk/by-uuid/3537-3761
UserspaceMountOptions: uhelper=udisks2
org.freedesktop.UDisks2.Filesystem:
MountPoints: /media/vanfan/Data
Size: 0
org.freedesktop.UDisks2.Partition:
Flags: 0
IsContained: false
IsContainer: false
Name:
Number: 1
Offset: 33554432
Size: 255835766784
Table: '/org/freedesktop/UDisks2/block_devices/mmcblk3'
Type: 0x07
UUID:
我可能遗漏了什么吗？ 有没有更好的方法？ 我之前和尝试让它工作时都曾尝试研究过这个主题，但我真的不明白为什么它不起作用。
答案1
Systemd 的 .mount 单元（至少源自 fstab 的单元）是设备绑定的。如果 udev 表示设备不可用，systemd 将停用挂载。
但是...该设备被标记为可用后udev 规则处理（因为这些规则可能经常与使其可用有关）。因此根据定义，设备将总是在“添加”规则处理期间尝试使用它时，systemd 将无法使用RUN。相反，您需要ENV{SYSTEMD_WANTS}。
有没有更好的方法呢？
只需创建一个正常的 fstab 条目。Udisks2将要识别它并将磁盘安装在 fstab 中指定的位置。
（您可能需要指定源以UUID=3537-3761安抚 Udisks 的 fstab 解析器。）